222 PRACTICAL ORGANIC CHEMISTRY
c.c.) and the contents of both flasks gradually added and well
washed out with hot water. The white precipitate changes to fhe
yellow iodide and the alcohol is driven off.
When the top liquid is no longer opalescent but clear, the
precipitate is collected in a Gooch crucible and dried and
weighed as described on p. 26.
For volatile substances like anisole this method cannot be em-
Example.—0*3150 gram naphthyl ether gave 0*468 gram AgT :
31 x 0*468 x IOQ
= 19*6 per cent.
I Calculated for C10HrOCH:5:CH3O = 19.6 per cent.
j ! P-Naphthyl Acetate. — Boil gently 5 grams /3-naphthol and
4 , 10 grams acetic anhydride for J hour with air condenser and
t \ pour the product into water. Crystallise from dilute alcohol ;
,VI(I "4 m. p. 70°.
'( | j A. Gr. Perkin's Acetyl method. (Proc. Chem. Soc., 1904,
' $ ' 2.0, 171). The method consists in hyclrolysing the acetyl
' \ I , derivative in presence of alcohol and distilling off the ethyl
^ ¥ ' acetate and then estimating the quantity by hydrolysis.
The apparatus is shown in Fig. 84. It consists of a small
distilling flask (200 c.c.) with bent side-tube which is fitted, to n
long condenser A tap-funnel is inserted into the neck and the
flask is heated over wire-gauze. About 0*5 gram of naphthyl
acetate is. accurately weighed out of a small sample tube by